The African Union [AU] may send an extra 1,700 troops to the crisis-hit Sudanese region of Darfur, where up to 50,000 people have been killed and more than a million have fled their homes.

The deployment is subject to the approval of the AU's peace and security council, which will also consider whether to widen the role of its force in Darfur. "The AU plans to increase troop strength of its protection force for Darfur from 300 to 2,000, with Nigeria and Rwanda offering to send 1,000 troops each," AU spokesman Adam Thiam told Reuters.

Today's announcement comes as more than 100,000 people marched though the streets of the Sudanese capital Khartoum in protest at a UN resolution ordering the government to stop the violence in the region.

Protesters on the state-sponsored demonstration chanted "no to America and its followers" before handing a memorandum to the UN's envoy demanding it stop spreading "misleading, antagonistic western propaganda".

The demonstration comes after the Sudanese government was persuaded, after talks with UN representative Jan Pronk, to double the number of its security forces in Darfur to 12,000 yesterday.

The government is reluctant to rein in the Arab Janjaweed militia, which is accused of waging a campaign of ethnic cleansing backed by the country's Islamist regime.

The conflict in Darfur began last year when rebel groups the Sudan Liberation Army and the Justice and Equality Movement began attacks on government targets, claiming that the regime was oppressing black Africans and supporting Arabs.

The Janjaweed was unleashed in response, and has subsequently forced over a million African farmers to flee their homes through a campaign of rape and mass slaughter.

The humanitarian crisis prompted the UN security council to order the Sudanese government to act, and the US Congress to conclude that genocide is taking place in the region.

The aid agency Oxfam also warned today that cholera could break out "at any time" in Darfur, as it sends another planeload of aid for the refugees.

Water and sanitation facilities at Kalma camp in Southern Darfur are "at breaking point", the charity warned, leading to the spread of diarrhoea and the imminent threat of cholera.

Today's aid delivery, the sixth sent by Oxfam to support the Darfur refugees, includes equipment that will be used to provide clean drinking water and build more than 1,000 toilets in Kalma camp

The emergency flight, paid for by the Department for International Development, is due to leave Manston airport in Kent this evening, headed for Nyala in Southern Darfur.

Oxfam confirmed that although the rainy season was causing transport difficulties, it was confident that the aid will reach the camp, which is 15km from the airport, quickly. "It's a bad road, but we can do it. We do anticipate being able to get the aid in place quite rapidly," a spokesman said.

Around 1.2 million people have been driven from their homes, with hundreds of thousands seeking refuge in makeshift camps in Sudan and over the border in Chad.

Sarah Lumsdon, Oxfam programme co-ordinator for Darfur, said: "Over the last three weeks the camp has doubled in size from 30,000 to 60,000 people. The camp infrastructure is unable to cope with such a boom in numbers. Basics like water supplies and sanitation are at breaking point."

She added: "With only a handful of toilets people are forced to defecate elsewhere; the result is human waste spread around the camp. The regular torrential rain washes the excrement into the camp and leads to dangerously unsanitary conditions. Disease and diarrhoea are serious problems and cholera could break out at any time," she said.

Paul Smith Lomas, the agency's humanitarian director, said: "The situation in Darfur is desperate and Kalma camp urgently needs this aid. People are already dying but we are dreading a cholera outbreak which could kill a lot more. This equipment will help us to save lives."

Oxfam is one of 11 major charities running an emergency appeal for aid to Sudan, coordinated by the umbrella organisation Disasters Emergency Committee (DEC). So far £12m has been raised from the public and appeal organisers predict that it will bring in at least £17m.

The DEC is continuing to appeal for more cash as aid agencies say they need up to £27m to meet the immediate needs of people in the area.